Photosensitive semiconductor nanocrystals, photosensitive composition comprising semiconductor nanocrystals and method for forming semiconductor nanocrystal pattern using the same

ABSTRACT

An organic-inorganic hybrid electroluminescent device having a semiconductor nanocrystal pattern prepared by producing a semiconductor nanocrystal film using semiconductor nanocrystals, where the nanocrystal is surface-coordinated with a compound containing a photosensitive functional group, exposing the film through a mask and developing the exposed film.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Division of U.S. patent application Ser. No.11/378,482, filed on 20 Mar. 2006, which is a Division of U.S. patentapplication Ser. No. 10/814,264, filed on 1 Apr. 2004, now U.S. Pat. No.7,199,393, which claims priority under 35 U.S.C. §119(a) to KoreanPatent Application No. 2003-73338 filed on Oct. 21, 2003, which are allherein incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to photosensitive semiconductornanocrystals, a photosensitive composition comprising semiconductornanocrystals and a method for forming a semiconductor nanocrystalpattern using the same. More particularly, the present invention relatesto semiconductor nanocrystals that are surface-coordinated with acompound containing a photosensitive functional group, a photosensitivecomposition comprising semiconductor nanocrystals, and a method forforming a semiconductor nanocrystal pattern by forming a film using thephotosensitive semiconductor nanocrystals or the photosensitivecomposition, exposing the film to light and developing the exposed film.

2. Description of the Related Art

Due to the quantum confinement effects of compound semiconductornanocrystals (i.e. quantum dots), the characteristic energy bandgap ofsemiconductor materials are changed. Since the control over thematerials, structure, shape and size of the nanocrystals enables thecontrol of the corresponding bandgaps, various energy levels can beobtained.

In recent years, there have been many trials to prepare semiconductornanocrystals by a wet chemistry method wherein a precursor material isadded to an organic solvent and nanocrystals are grown so as to have anintended size. According to the wet chemistry method, as thenanocrystals are grown, the organic solvent is naturally coordinated tothe surface of the nanocrystals and acts as a dispersant. Accordingly,the organic solvent allows the nanocrystals to grow in thenanometer-scale level. Using vapor deposition processes, e.g., MOCVD(metal organic chemical deposition) and MBE (molecular beam epitaxy), itis difficult to uniformly control the size, shape and density ofnanocrystals. In contrast, the wet chemistry method has an advantage inthat nanocrystals can be uniformly synthesized in various sizes byappropriately controlling the concentration of precursors used, the kindof organic solvents, synthesizing temperature and time, etc.

However, since nanocrystals prepared by the wet chemistry method arecommonly dispersed in an organic solvent, such as toluene or chloroform,techniques of forming a thin film as well as pattern forming method ofnanocrystals are required in order to apply the nanocrystals toelectronic devices. Patterning techniques reported hitherto are mainlyassociated with the patterning of nanocrystals by vapor deposition.These techniques, however, have a shortcoming in that control over theuniformity of size, shape, and density is difficult (Appl. Phys. Letter,1997, 70, 3140).

In this regard, U.S. Pat. No. 5,559,057 suggests a method for forming apattern of nanocrystals which comprises the steps of vapor-depositing orspraying nanocrystals using a mask to deposit nanocrystals only on theareas not covered with a mask, irradiating the nanocrystals with anelectron beam to produce a thin film, and removing the mask. U.S. Pat.No. 6,139,626 discloses a method for indirectly forming a pattern ofnanocrystals by filling in pores of a template with nanocrystals whereinthe template may be patterned in any configuration. However, thesepatterning methods involve the use of a high-energy electron beam and atroublesome lift-off operation of the mask used. In addition, thetemplate material may affect the performances of the pattern to beformed, and there is thus a limitation in the kind of materials that canbe patterned.

Further, U.S. Pat. No. 5,751,018 discloses a method for aligningnanocrystals using terminal groups of a self-assembled monolayer formedon a metal substrate. U.S. Pat. No. 6,602,671 describes a method forbinding dispersed nanocrystals to a polymeric support. Since theabove-mentioned methods are not substantially associated withpatterning, they have limited applicability to the patterning ofnanocrystals.

Thus, there exists a need in the art for a method for forming a patternof semiconductor nanocrystals in a simple manner, without the use of atemplate or a deposition process requiring high vacuum and hightemperature conditions.

SUMMARY OF THE INVENTION

A feature of the present invention is to provide novel photosensitivesemiconductor nanocrystals for forming a semiconductor nanocrystalpattern.

Another feature of the present invention is to provide a novelphotosensitive composition comprising semiconductor nanocrystals forforming a semiconductor nanocrystal pattern.

Still another feature of the present invention is to provide a methodfor forming a semiconductor nanocrystal pattern using the abovephotosensitive semiconductor nanocrystals and the photosensitivecomposition.

In accordance with a feature of the present invention, there is providedsemiconductor nanocrystals surface-coordinated with a compoundcontaining a photosensitive functional group.

In accordance with another feature of the present invention, there isprovided a photosensitive composition for a semiconductor nanocrystalpattern, comprising i) semiconductor nanocrystals, and ii) aphotocurable compound.

In accordance with still another feature of the present invention, thereis provided a method for forming a semiconductor nanocrystal pattern,comprising the steps of: i) producing a semiconductor nanocrystal filmusing the above semiconductor nanocrystals or the above photosensitivecomposition; ii) exposing the film through a mask; and iii) developingthe exposed film.

In accordance with still another feature of the present invention, thereis provided an organic-inorganic hybrid electroluminescent device,wherein the semiconductor nanocrystal pattern prepared according to theabove method is contained as a luminescent layer.

BRIEF DESCRIPTION OF THE DRAWINGS

The patent or patent application file contains at least one drawingexecuted in color. Copies of this patent or patent applicationpublication with color drawing)s) will be provided by the Office uponrequest and payment of the necessary fee.

The above and other objects, features and other advantages of thepresent invention will be more clearly understood from the followingdetailed description taken in conjunction with the accompanyingdrawings, in which:

FIG. 1 is a schematic diagram of a semiconductor nanocrystalsurface-coordinated with a compound containing a photosensitivefunctional group;

FIG. 2 is a photograph of a semiconductor nanocrystal pattern preparedin Example 1 of the present invention (enlarged by 1000 times, takenwith UV microscope);

FIG. 3 is a photograph of a semiconductor nanocrystal pattern preparedin Example 3 of the present invention (enlarged by 1000 times, takenwith UV microscope);

FIG. 4 is a photograph of a semiconductor nanocrystal pattern preparedin Example 4 of the present invention (enlarged by 1000 times, takenwith UV microscope);

FIGS. 5 a and 5 b are an optical microscopic image (×1,000) and an AFMimage of the semiconductor nanocrystal pattern of FIG. 4; and

FIG. 6 is an electroluminescent spectrum of an electroluminescent devicemanufactured in Example 8 of the present invention.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

Hereinafter, the present invention will be explained in more detail withreference to the accompanying drawings.

Photosensitive Semiconductor Nanocrystals

The photosensitive semiconductor nanocrystals of the present inventionare semiconductor nanocrystals surface-coordinated with a compoundcontaining a photosensitive functional group.

Semiconductor nanocrystals usable in the present invention may includeall semiconductor nanocrystals prepared from metal precursors by a wetchemistry method. For example, the semiconductor nanocrystals may beprepared by adding a corresponding metal precursor to an organic solventin the absence or presence of a dispersant, and growing crystals at apredetermined temperature. Examples of suitable semiconductornanocrystals usable in the present invention include Group II-IV, III-IVand V compound nanocrystals and mixtures thereof. More preferredexamples of nanocrystals include, but are not limited to, CdS, CdSe,CdTe, ZnS, ZnSe, ZnTe, HgS, HgSe, HgTe, GaN, GaP, GaAs, InP, InAs andmixtures thereof. If the semiconductor nanocrystals are composed of twoor more compounds, it may be a uniformly mixed type, gradiently mixedtype, core-shell type or ally type.

The photosensitive compound coordinated to the surface of thesemiconductor nanocrystals is a compound wherein a photoreactivefunctional group (e.g., carbon-carbon double bond or acryl group) isselectively bonded to a linker (e.g., cyanide, thiol (SH), amino,carboxylic acid group or phosphonic acid group). Selectively, there maybe an alkylene, amide, phenylene, biphenylene, ester or ether groupbetween the photoreactive functional group and the linker. Preferably,the photosensitive compound is represented by Formula 1 below:X-A-B  (1)wherein X is NC—, HOOC—, HRN—, POOOH—, RS— or RSS— (in which R is ahydrogen atom or a C_(1˜10) saturated or unsaturated aliphatichydrocarbon group); A is a direct bond, an aliphatic organic group, aphenylene group or a biphenylene group; and B is an organic groupcontaining at least one carbon-carbon double bond, which may besubstituted with at least one group selected from the group consistingof —CN, —COOH, halogen groups, C_(1˜5) halogenated alkyl groups, aminegroups, C_(6˜15) aromatic hydrocarbon groups, and C_(6˜12) aromatichydrocarbon groups substituted with F, Cl, Br, a halogenated alkylgroup, R′O— (in which R′ is a hydrogen atom or a C_(1˜5) alkyl group),—COOH, an amine group or —NO₂.

More preferably, the aliphatic organic group in the substituent A ofFormula 1 is a saturated aliphatic hydrocarbon group such as —(CR₂)_(n)—(in which R is a hydrogen atom, a C_(1˜5) alkyl group, and n is aninteger of 1˜30), an aliphatic ester group containing an ester moiety(—COO—), an aliphatic amide group containing an amide moiety (—NHCO—),an aliphatic oxycarbonyl group containing an oxycarbonyl moiety (—OCO—),or an aliphatic ether group containing an ether moiety (—O—). Thealiphatic organic group may be branched with a C_(1˜5) alkyl group, ormay be substituted with by a hydroxyl, amine or thiol group.

More preferably, the moiety B in Formula 1 is an organic grouprepresented by Formula 2 below:—CR₁═CR₂R₃  (2)wherein R₁ is a hydrogen atom, —COOH, a halogen group, a C_(1˜5) alkylgroup or a halogenated alkyl group; and R₂ and R₃ are each independentlya hydrogen atom, a C_(1˜30) alkyl group, —CN, —COOH, a halogen group, aC_(1˜5) halogenated alkyl group, a C_(2˜30) unsaturated aliphatichydrocarbon group containing at least one carbon-carbon double bond, aC_(6˜12) aromatic hydrocarbon group substituted or unsubstituted with F,Cl, Br, hydroxyl, a C1˜5 halogenated alkyl group, an amine group, R′O—(in which R′ is a C_(1˜5) alkyl group), —COOH or —NO₂.

In the moieties R₂ and R₃ of Formula 2, the C_(1˜30) alkyl group and theC_(2˜30) unsaturated aliphatic hydrocarbon group containing at least onecarbon-carbon double bond may be branched by an alkyl group, and ifnecessary, may be substituted with a hydroxyl group, a carboxyl group,etc. The number of the double bonds in the unsaturated aliphatichydrocarbon group is not especially limited, but is preferably 3 orless.

Preferred examples of the compound represented by Formula 1 include, butare not limited to, methacrylic acid, crotonic acid, vinylacetic acid,tiglic acid, 3,3-dimethylacrylic acid, trans-2-pentenoic acid,4-pentenoic acid, trans-2-methyl-2-pentenoic acid,2,2-dimethyl-4-pentenoic acid, trans-2-hexenoic acid, trans-3-hexenoicacid, 2-ethyl-2-hexenoic acid, 6-heptenoic acid, 2-octenoic acid,citronellic acid, undecylenic acid, myristoleic acid, palmitoleic acid,oleic acid, elaidic acid, cis-11-elcosenoic acid, euric acid, nervonicacid, trans-2,4-pentadienoic acid, 2,4-hexadienoic acid,2,6-heptadienoic acid, geranic acid, linoleic acid, 11,14-eicosadienoicacid, cis-8,11,14-eicosatrienoic acid, arachidonic acid,cis-5,8,11,14,17-eicosapentaenoic acid,cis-4,7,10,13,16,19-docosahexaenoic acid, fumaric acid, maleic acid,itaconic acid, ciraconic acid, mesaconic acid, trans-glutaconic acid,trans-beta-hydromuconic acid, trans-traumatic acid, trans-muconic acid,cis-aconitic acid, trans-aconitic acid, cis-3-chloroacrylic acid,trans-3-chloroacrylic acid, 2-bromoacrylic acid,2-(trifluoromethyl)acrylic acid, trans-styrylacetic acid, trans-cinnamicacid, α-methylcinnamic acid, 2-methylcinnamic acid, 2-fluorocinnamicacid, 2-(trifluoromethyl)cinnamic acid, 2-chlorocinnamic acid,2-methoxycinnamic acid, 2-hydroxycinnamic acid, 2-nitrocinnamic acid,2-carboxycinnamic acid, trans-3-fluorocinnamic acid,3-(trifluoromethyl)cinnamic acid, 3-chlorocinnamic acid, 3-bromocinnamicacid, 3-methoxycinnamic acid, 3-hydroxycinnamic acid, 3-nitrocinnamicacid, 4-methylcinnamic acid, 4-fluorocinnamic acid,trans-4-(trifluoromethyl)-cinnamic acid, 4-chlorocinnamic acid,4-bromocinnamic acid, 4-methoxycinnamic acid, 4-hydroxycinnamic acid,4-nitrocinnamic acid, 3,3-dimethoxycinnamic acid, 4-vinylbenzoic acid,allyl methyl sulfide, allyl disulfide, diallyl amine, oleylamine,3-amino-1-propanol vinyl ether, 4-chlorocinnamonitrile,4-methoxycinnamonitrile, 3,4-dimethoxycinnamonitrile,4-dimethylaminocinnamonitrile, acrylonitrile, allyl cyanide,crotononitrile, methacrylonitrile, cis-2-pentenenitrile,trans-3-pentenenitrile, 3,7-dimethyl-2,6-octadienenitrile and1,4-dicyano-2-butene.

The photosensitive semiconductor nanocrystals of the present inventioncan be prepared by obtaining nanocrystals from a corresponding metalprecursor, dispersing the obtained nanocrystals in an organic solvent,and treating the dispersion with the photosensitive compound ofFormula 1. The treatment with the photosensitive compound is notespecially limited, but is preferably carried out by refluxing thedispersion of the nanocrystals in the presence of the photosensitivecompound. The reflux conditions, including time and temperature, and theconcentration of the photosensitive compound can be properly controlledaccording to the kind of the dispersing solvent, the nanocrystals andthe photosensitive compound coordinated to the surface of thenanocrystals. Alternatively, nanocrystals are surface-coordinated with adispersant having a reactive end group, such as mercaptopropanol, andthen reacted with a photosensitive compound capable of reacting with thereactive end group of the dispersant, such as methacryloyl chloride,thereby producing nanocrystals surface-coordinated with thephotosensitive compound.

Still alternatively, semiconductor nanocrystals may be directlysurface-coordinated with a photosensitive compound by adding a metalprecursor into an organic solvent and growing crystals at thepredetermined temperature in the presence of the photosensitivecompound. The kind of organic solvent, the crystal-growth temperatureand the concentration of the precursor can be appropriately variedaccording to the kind of the photosensitive compound, and the kind, sizeand shape of the desired semiconductor nanocrystals.

A preferred embodiment of the photosensitive semiconductor nanocrystalsaccording to the present invention is schematically shown in FIG. 1. Asshown in FIG. 1, X is a linker binding the semiconductor nanocrystals toa photosensitive functional group such as aryl or vinyl group. Thesurface-coordinating rate of the photosensitive compound to thesemiconductor nanocrystals can be appropriately controlled by changingthe mixing ratio of the nanocrystals and the compound.

Photosensitive Composition for Pattern Formation of SemiconductorNanocrystals

The photosensitive composition of the present invention comprises i)semiconductor nanocrystals, and ii) a photocurable compound

As to the semiconductor nanocrystals, common semiconductor nanocrystalsor photosensitive semiconductor nanocrystals according to the presentinvention may be used. Where photosensitive semiconductor nanocrystalsof the present invention are used, it is advantageous that substitutionwith a compound containing a photosensitive functional group isunnecessary. The semiconductor nanocrystals contained in thephotosensitive composition of the present invention are as describedabove.

As to the photocurable compound contained in the photosensitivecomposition, polymers containing at least one acryl and/or vinyl groupand ether-based compounds can be used. More concretely, polymerscontaining at least one acryl and/or vinyl group include multifunctionalacrylate-based compounds, multifunctional polyalkyleneoxide compoundsand polysiloxanes containing at least one acryl and/or vinyl group.

Preferred examples of the photocurable compound include, but are notlimited to, allyloxylated cyclohexyl diacrylate, bis(acryloxyethyl)hydroxyl isocyanurate, bis(acryloxy neopentylglycol) adipate,bisphenol A diacrylate, bisphenyl A dimethacrylate, 1,4-butanedioldiacrylate, 1,4-butanediol dimethacrylate, 1,3-butyleneglycoldiacrylate, 1,3-butyleneglycol dimethacrylate, dicyclopentanyldiacrylate, diethyleneglycol diacrylate, diethyleneglycoldimethacrylate, dipentaerythirol hexaacrylate, dipentaerythirolmonohydroxy pentacrylate, ditrimethylolpropane tetraacrylate,ethyleneglycol dimethacrylate, glycerol methacrylate, 1,6-hexanedioldiacrylate, neopentylglycol dimethacrylate, neopentylglycolhydroxypivalate diacrylate, pentaerythritol triacrylate, pentaerythritoltetraacrylate, phosphoric acid dimethacrylate, polyetyleneglycoldiacrylate, polypropyleneglycol diacrylate, tetraethyleneglycoldiacrylate, tetrabromobisphenol A diacrylate, triethyleneglycoldivinylether, triglycerol diacrylate, trimethylolpropane triacrylate,tripropyleneglycol diacrylate, tris(acryloxyethyl)isocyanurate,phosphoric acid triacrylate, phosphoric acid diacrylate, acrylic acidpropargyl ester, vinyl terminated polydimethylsiloxane, vinyl terminateddiphenylsiloxane-dimethylsiloxane copolymer, vinyl terminatedpolyphenylmethylsiloxane, vinyl terminatedtrifluoromethylsiloxane-dimethylsiloxane copolymer, vinyl terminateddiethylsiloxane-dimethylsiloxane copolymer, vinylmethylsiloxane,monomethacryloyloxypropyl terminated polydimethyl siloxane, monovinylterminated polydimethyl siloxane and monoallyl-mono trimethylsiloxyterminated polyethylene oxide.

The composition ratio of i) the semiconductor nanocrystals and ii) thephotocurable compound contained in the photosensitive composition of thepresent invention is not especially limited, and can be properlycontrolled depending on the photocurability (i.e. curing rate, state ofa cured film, etc.), binding ability between the photosensitive compoundand the nanocrystals, etc.

Pattern Formation of Semiconductor Nanocrystals

A semiconductor nanocrystal pattern can be formed by a) forming asemiconductor nanocrystal film using the photosensitive semiconductornanocrystals or the photosensitive composition according to the presentinvention; b) exposing the film through mask; and c) developing theexposed film.

In step a), the semiconductor nanocrystal film is produced by dispersingthe photosensitive semiconductor nanocrystals or the photosensitivecomposition according to the present invention in a suitable organicsolvent, and coating the dispersion onto a substrate. At this step, aphotoinitiator may be added to the organic solvent. Unlike commonphotolithgraphic techniques, the photosensitive semiconductornanocrystals or the photosensitive composition according to the presentinvention may be cured without a photoinitiator. However, if necessary,a photoinitiator may be used to assist the crosslinking reaction.Examples of photoinitiators usable in the present invention includethose capable of forming free radicals upon light irradiation, such asacetophenone-, benzoin-, benzophenone- and thioxantone-basedphotoinitiators. Examples of the acetophenone-based initiator usable inthe present invention include 4-phenoxy dichloroacetophenone, 4-t-butyldichloroacetophenone, 4-t-butyl trichloroacetophenone,diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenyl-propane-1-one,1-(4-isopropylphenyl)-2-hydroxy-2-methyl-propane-1-one,1-(4-dodecylphenyl)-2-hydroxy-2-methylpropane-1-one,4-(2-hydroxyethoxy)-phenyl-(2-hydroxy-2-propyl)ketone, 1-hydroxycyclohexyl phenyl ketone,2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-propane-1, and the like.Examples of the benzoin-based photoinitiator include benzoin, benzoinmethyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoinisobutyl ether, benzyl dimethyl ketal, etc. Examples of thebenzophenone-based photoinitiator include benzophenone, benzoyl benzoicacid, benzoyl benzoic acid methyl ester, 4-phenyl benzophenone, hydroxybenzophenone, 4-benzoyl-4′-methyl diphenyl sulphide,3,3′-dimethyl-4-methoxy benzophenone and the like.

An organic solvent used in this process is not especially limited, butpreferably those capable of homogeneously dispersing nanocrystals andbeing easily removed after application are used. More preferably, DMF,4-hydroxy-4-methyl-2-pentanone, ethylene glycol monoethyl ether,2-methoxyethanol, chloroform, chlorobenzene, toluene, teterahydrofuran,dichloromethane, hexane, heptane, octane, nonane, decane or a mixturethereof is used. The application may be carried out by a spin coating,dip coating, spray coating or blade coating process, but is notespecially limited thereto. The film thus obtained is dried at 30-300°C. and preferably 40-120° C. to evaporate the organic solvents ahead oflight exposure.

In step b), the film is selectively exposed to an electromagnetic wavethrough a photomask having a desired pattern. At this time, acrosslinking reaction takes place through photosensitive functionalgroups or photocurable compounds in the exposed area. This crosslinkingreaction enables the formation of a network structure of semiconductornanocrystals, resulting in a solubility difference between the exposedand unexposed areas. Based on the solubility difference, development ofthe film with a developing agent enables the formation of a negativepattern of semiconductor nanocrystals. The light exposure may be carriedout by a contact or non-contact exposure process. In addition, theexposure dose is not especially limited, and can be appropriatelycontrolled according to the thickness of the film formed. It ispreferred that the light exposure is carried out at an exposure dose of50-850 mJ/cm². When the exposure dose is insufficient, a crosslinkingreaction is not likely to take place, or a photo bleaching occurs, whichcauses poor luminescence efficiency of the patterned nanocrystals. Alight source usable for the light exposure preferably has an effectivewavelength range of 200-500 nm, preferably 300˜400 nm, and has an energyrange of 100-800 W.

In step c), the exposed film is developed with an appropriate developingagent to form a semiconductor nanocrystal pattern. Examples ofdeveloping agents usable in the present invention include organicsolvents, such as toluene and chloroform, weakly acidic solutions andweakly basic solutions, and pure water.

Since the semiconductor nanocrystal pattern formed by the method of thepresent invention exhibits excellent luminescence characteristics, itcan be utilized in a variety of fields, including semiconductor devices,e.g., displays, sensors and solar cells. Particularly, the pattern isuseful in forming the luminescent layer of an organic-inorganic hybridelectroluminescent device. When the pattern is used to form aluminescent layer, it preferably has a thickness of 5-100 nm. In theorganic-inorganic hybrid electroluminescent device, organic layers areformed in an electron transport layer or a hole transport layer exceptluminescent layer.

The organic electroluminescent device has a structure selected fromanode/luminescent layer/cathode, anode/buffer layer/luminescentlayer/cathode, anode/hole transport layer/luminescent layer/cathode,anode/buffer layer/hole transport layer/luminescent layer/cathode,anode/buffer layer/hole transport layer/luminescent layer/electrontransport layer/cathode, and anode/buffer layer/hole transportlayer/luminescent layer/hole blocking layer/cathode, but is notparticularly limited to these structures.

As for buffer layer materials, compounds commonly used in the art forthis purpose can be used. Preferred examples include, but are notlimited to, copper phthalocyanine, polythiophene, polyaniline,polyacetylene, polypyrrole, polyphenylene vinylene and derivativesthereof. As materials for the hole transport layer, compounds commonlyused in the art for this purpose can be used but the preferred ispolytriphenylamine. As materials for the electron transport layer,compounds commonly used in the art for this purpose can be used but thepreferred is polyoxadiazole. As materials for the hole blocking layer,compounds commonly used in the art for this purpose can be used.Preferred examples include, but are not limited to, LiF, BaF₂, MgF₂ andthe like.

The organic-inorganic hybrid electroluminescent device of the presentinvention does not require particular manufacturing apparatuses andmethods and can be manufactured using materials commonly known in theart, in accordance with conventional manufacturing methods.

Hereinafter, the present invention will be described in more detail withreference to the following examples and preparative examples. However,these examples are given for the purpose of illustration and are not tobe construed as limiting the scope of the invention.

Preparative Example 1 Preparation of Green Emitting CdSeS NanocrystalsSurface-Coordinated with a Compound Containing a Double Bond

16 g of trioctylamine (hereinafter, referred to as ‘TOA’), 0.5 g ofoleic acid and 0.4 mmol of cadmium oxide were introduced simultaneouslyinto a 125 ml flask equipped with a reflux condenser. The temperature ofthe mixture was raised to 300° C. with stirring. Separately, selenium(Se) powder was dissolved in trioctyl phosphine (hereinafter, referredto as ‘TOP’) to obtain Se-TOP complex solution (Se concentration: about0.25 M), and sulfur (S) powder was dissolved in TOP to obtain S-TOPcomplex solution (S concentration: about 1.0 M). 0.9 ml of the S-TOPcomplex solution and 0.1 ml of the Se-TOP complex solution were rapidlyadded to the reactant mixture, and then reacted for 4 minutes withstirring. Immediately after the reaction was completed, the reactionmixture was rapidly cooled to room temperature. Ethanol as a non-solventwas added to the reaction mixture, and the resulting mixture was thencentrifuged. After the obtained precipitate was separated from themixture by decanting the supernatant, it was dispersed in toluene in theconcentration of 1 wt %. Peak emitting wavelength was about 520 nm inthe electroluminescence spectrum of the nanocrystals, and thenanocrystals emitted green light under 365 nm UV lamp.

Preparative Example 2 Preparation of Blue Emitting CdSeS NanocrystalsSurface-Coordinated with a Compound Containing a Double Bond

CdSeS nanocrystals were prepared in the same manner as in PreparativeExample 1, except that the concentration of Se in the Se-TOP complexsolution was set to 0.06 M, and the concentration of S in the S-TOPcomplex solution was set to 2.0 M. Peak emitting wavelength was about480 nm in the electroluminescence spectrum of the nanocrystals, and thenanocrystals emitted blue light under 365 nm UV lamp.

Preparative Example 3 Preparation of CdS NanocrystalsSurface-Coordinated with a Compound Containing a Double Bond

2.5 ml of TOA was introduced into a 25 ml flask equipped with a refluxcondenser, and then the temperature was raised to 180° C. with stirring.A solution of 50 mg of cadmium dithio diethyl carbamate in 0.9 ml of TOPwas rapidly added to the TOA, and then reacted for 10 minutes withstirring. Immediately after the reaction was completed, the reactionmixture was rapidly cooled to room temperature. Ethanol as a non-solventwas added to the reaction mixture, and the resulting mixture was thencentrifuged. After the obtained precipitate was separated from themixture by decanting the supernatant, it was dispersed in toluene in theconcentration of 1 wt %. Then, oleic acid was added to the dispersion inthe concentration of 5 mM. The resulting mixture was refluxed at 70° C.with stirring. For better surface-binding ability, the nanocrystals wereseparated from the solvent and dispersed again in toluene followed byadding oleic acid in the concentration of 5 mM and refluxing the mixturefor 24 hours at 70° C. with stirring. The above procedure was repeatedseveral times to prepare desired nanocrystals of which the surface wassubstituted with oleic acid. The final nanocrystals were dispersed intoluene. The peak emitting wavelength in the electroluminescent spectrumof the nanocrystals was 510 nm, and the nanocrystals emittedbluish-green light under 365 nm UV lamp.

Preparative Example 4 Preparation of CdSeS NanocrystalsSurface-Coordinated with a Compound Containing Acryl and Vinyl Groups

To the dispersion of the nanocrystals prepared in Preparative Example 1,3-mercapto-1-propanol was added in the concentration of 32 mM. After theresulting mixture was refluxed at room temperature with stirring for 10hours, the nanocrystals coordinated with 3-mercapto-1-propanol wereseparated through centrifuge and then dispersed in toluene in theconcentration of 1 wt %. 2 g of the dispersion were introduced into a250 ml three-neck flask in an ice bath, and 50 g of tetrahydrofuran and0.1 g of triethylamine (TEA) were added thereto. The reactant mixturewas stirred under nitrogen gas for 30 minutes. After 0.15 g ofmethacryloyl chloride was added dropwise to the mixture using a droppingfunnel, the reaction was continued for 4 hours. Then, adducts of saltswere filtered off using a 0.1 μm filter. Thereafter, the reactionmixture was washed with 100 ml of distilled water in a separatory funnelto remove unreacted reactants and residual salts. The supernatant wasseparated from the dispersion in which semiconductor nanocrystals weredispersed, and remaining solvents were removed in a rotary evaporatorunder nitrogen gas to obtain nanocrystals. The resulting nanocrystalswere again dispersed in toluene. The above procedure was repeatedseveral times to obtain a toluene dispersion of final nanocrystals ofwhich the surface was substituted with acryl and vinyl groups.

Preparative Example 5 Preparation of CdS NanocrystalsSurface-Coordinated with a Compound Containing Acryl Group

2.5 ml of TOA was introduced into a 25 ml flask equipped with a refluxcondenser, and then the temperature was raised to 180° C. with stirring.A solution of 50 mg of cadmium dithio diethyl carbamate in 0.9 ml of TOPwas rapidly added to the TOA, and then reacted for 10 minutes withstirring. Immediately after the reaction was completed, the reactionmixture was rapidly cooled to room temperature. Ethanol as a non-solventwas added to the reaction mixture, and the resulting mixture was thencentrifuged. After the obtained precipitate was separated from themixture by decanting the supernatant, it was dispersed in toluene in theconcentration of 1 wt %.

3-Mercapto-1-propanol was added to the dispersion in the concentrationof 32 mM. After the resulting mixture was refluxed at room temperaturefor 10 hours with stirring, it was centrifuged to separate thenanocrystals surface-coordinated with the 3-mercapto-1-propanol. Theobtained nanocrystals were again dispersed in toluene in theconcentration of 1 wt %. Thereafter, 50 g of tetrahydrofuran and 0.1 gof triethylamine (TEA) were added to 2 g of the dispersion. The mixturewas stirred under nitrogen gas for 30 minutes. After 0.15 g ofmethacryloyl chloride was added dropwise to the mixture using a droppingfunnel, the reaction was continued for 4 hours. At this time, adducts ofsalts were filtered off using a 0.1 μm filter. The reaction mixture waswashed with 100 ml of distilled water in a separatory funnel to removeunreacted reactants and residual salts. The supernatant was separatedfrom the dispersion in which semiconductor nanocrystals were dispersed,and remaining solvents were removed in a rotary evaporator undernitrogen gas to prepare nanocrystals. The resulting nanocrystals wereagain dispersed in toluene. The above procedure was repeated severaltimes to obtain a toluene dispersion of final nanocrystals of which thesurface was substituted with acryl group.

Example 1 Formation of a Green Emitting CdSeS Nanocrystal Pattern

The dispersion (1 wt %) of CdSeS nanocrystals prepared in PreparativeExample 1 was spin coated onto a glass substrate cleaned with IPA at2,000 rpm for 30 seconds to provide a semiconductor nanocrystal film.The film was dried at 50° C. for 1 minute, and then at 100° C. for 1minute to completely evaporate solvents. Then, the film was exposed to800 W UV light having an effective wavelength of 200-300 nm through amask having a desired pattern for 300 seconds. The exposed film wasdeveloped with toluene to form a semiconductor nanocrystal pattern. FIG.2 is a photograph showing the emitting state of the pattern under a 365nm UV lamp. From the photograph, it was confirmed that the nanocrystalpattern was consistent with that of the photomask used, and emittedgreen light. The peak emitting wavelength was about 520 nm, showing thesame result as that of the electroluminescent spectrum of thenanocrystals prepared in Preparative Example 1. In addition, theemitting peak had a full width half maximum (hereinafter, referred to as“FWHM”) of approximately 40 nm.

Example 2 Formation of Nanocrystal Pattern Using a PhotosensitiveComposition

2.5 ml of TOA was introduced into a 25 ml flask equipped with a refluxcondenser, and then the temperature was raised to 180° C. with stirring.A solution of 50 mg of cadmium dithio diethyl carbamate in 0.9 ml of TOPwas rapidly added to TOA, and then reacted for 10 minutes with stirring.Immediately after the reaction was completed, the reaction mixture wasrapidly cooled to room temperature. Ethanol as a non-solvent was addedto the reaction mixture, and the resulting mixture was then centrifuged.After the obtained precipitate was separated from the mixture bydecanting the supernatant, it was dispersed in toluene in theconcentration of 1 wt %. 2 g of the dispersion and 0.0005 g ofdipentaerythritol hexaacrylate (DPHA) were homogeneously mixed toprepare a composition. Then, the composition was spin coated onto aglass substrate cleaned with IPA, at 2,000 rpm for 30 seconds to providea film. The film was exposed to 800 W UV light having effectivewavelength of 200-300 nm through a mask having a desired pattern for 300seconds. The exposed film was developed with toluene to form asemiconductor nanocrystal pattern. It was observed that the nanocrystalpattern emitted bluish-green light under 365 nm UV lamp. It wasconfirmed from the observation that the nanocrystal pattern wasconsistent with that of the photomask used. The peak emitting wavelengthwas about 510 nm in the electroluminescent spectrum of the pattern.

Example 3 Formation of Green Emitting CdSeS Nanocrystal Pattern Using aPhotosensitive Composition

0.2 g of the toluene solution (1 wt %) of CdSeS nanocrystals prepared inPreparative Example 1, and 0.0005 g of dipentaerythritol hexaacrylate(DPHA) were homogeneously mixed to prepare a photosensitive composition.The composition was spin coated onto a glass substrate cleaned with IPA,at 2,000 rpm for 30 seconds to provide a film. Then, the film wasexposed to 800 W UV light having an effective wavelength of 200-300 nmthrough a mask having a desired pattern for 300 seconds. The exposedfilm was developed with toluene to form a semiconductor nanocrystalpattern. FIG. 3 is a photograph showing the emitting state of thenanocrystal pattern under a 365 nm UV lamp. From the photograph, it wasconfirmed that the nanocrystal pattern was consistent with that of thephotomask used, and emitted green light. The peak emitting wavelengthwas about 520 nm, showing the same result as that of theelectroluminescent spectrum of the nanocrystals prepared in PreparativeExample 1. In addition, the emitting peak had FWHM of approximately 40nm.

Example 4 Formation of Blue Emitting CdSeS Nanocrystal Pattern Using aPhotosensitive Composition

0.05 g of the toluene solution (1 wt %) of CdSeS nanocrystals preparedin Preparative Example 2, and 0.001 g of DPHA were homogeneously mixedto prepare a composition. The composition was spin coated onto a glasssubstrate cleaned with IPA, at 2,000 rpm for 30 seconds to provide afilm. Then, the film was exposed to 800 W UV light having an effectivewavelength of 200-300 nm through a mask having a desired pattern for 300seconds. The exposed film was developed with toluene to form asemiconductor nanocrystal pattern. FIG. 4 is a photograph showing theemitting state of the nanocrystal pattern under a 365 nm UV lamp. Fromthe photograph, it was confirmed that the nanocrystal pattern wasconsistent with that of the photomask used, and emitted blue light. Thepeak emitting wavelength was about 480 nm, and had FWHM of approximately40 nm. FIGS. 5 a and 5 b are an optical microscopic image (×1,000) andan AFM image of the semiconductor nanocrystal pattern. From the FIGS. 5a and 5 b, it was known that the CdSeS nanocrystals were uniformlydispersed in CdSeS nanocrystal pattern.

Example 5 Patterning of CdS Nanocrystals Surface-Coordinated with aCompound Containing a Carbon-Carbon Double Bond

0.05 g of the toluene solution (1 wt %) of CdS nanocrystalssurface-coordinated with oleic acid prepared in Preparative Example 3,was spin coated onto a glass substrate cleaned with IPA, at 2,000 rpmfor 30 seconds to provide a semiconductor nanocrystal film. The film wasdried at 50° C. for 1 minute, and then at 100° C. for 1 minute tocompletely evaporate solvents. Then the film was exposed to 800 W UVlight having an effective wavelength of 200-300 nm through a mask havinga desired pattern for 300 seconds. The exposed film was developed withtoluene to form semiconductor nanocrystal pattern. It was confirmed thatthe nanocrystal pattern was consistent with that of the photomask used,and emitted bluish-green light.

Example 6 Patterning of CdSeS Nanocrystals Surface-Coordinated with aCompound Containing an Acryl Group

0.05 g of the toluene solution (1 wt %) of CdSeS nanocrystalssurface-coordinated with a compound containing an acryl group, asprepared in Preparative Example 4, was spin coated onto a glasssubstrate cleaned with IPA, at 2,000 rpm for 30 seconds to providesemiconductor nanocrystal film. The film was dried at 50° C. for 1minute and then at 100° C. for 1 minute to completely evaporatesolvents. Then, the film was exposed to 800 W UV light having aneffective wavelength of 200-300 nm through a mask having a desiredpattern for 300 seconds. The exposed film was developed with toluene toform semiconductor nanocrystal pattern. It was confirmed that thenanocrystal pattern was consistent with that of the photomask used, andemitted green light.

Example 7 Patterning of CdS Nanocrystals Surface-Coordinated with aCompound Containing Acryl Group

0.05 g of the toluene solution (1 wt %) of CdS nanocrystalssurface-coordinated with a compound containing an acryl group, asprepared in Preparative Example 5, was spin coated onto a glasssubstrate cleaned with IPA, at 2,000 rpm for 30 seconds to provide asemiconductor nanocrystal film. The film was dried at 50° C. for 1minute and then at 100° C. for 1 minute to completely evaporatesolvents. Then, the film was exposed to 800 W UV light having effectivewavelength of 200˜300 nm through a mask having a desired pattern for 300seconds. The exposed film was developed with toluene to form asemiconductor nanocrystal pattern. It was confirmed that the nanocrystalpattern was consistent with that of the photomask used, and emittedgreen light.

Example 8 Manufacture of Electroluminescent Device Using NanocrystalPattern

In this Example, an organic-inorganic hybrid electroluminescent devicewas manufactured by employing a thin pattern of the nanocrystalsprepared in Preparative Example 1 as a luminescent material. PEDOT(poly-3,4-ethylenedioxythiophene) as a hole transport layer wasspin-coated onto a patterned ITO substrate to a thickness of 50 nm, andthen baked. The toluene solution (1 wt %) of CdSeS nanocrystals preparedin Preparative Example 1 was spin-coated onto the hole transport layerand dried to form a luminescent layer having a thickness of 5 nm. Theluminescent layer was exposed to 800 W UV light having an effectivewavelength range of 200-300 nm through a mask for 200 seconds and theexposed film was developed with toluene. Alq3 (tris(8-hydroxyquinoline)aluminum) was deposited onto the luminescent layer to form an electrontransport layer having a thickness of about 40 nm. LiF and aluminum weresequentially deposited onto the electron transport layer to thickness of1 nm and 200 nm, respectively, to manufacture an organic-inorganichybrid electroluminescent device.

An electroluminescent spectrum of the electroluminescent device is shownin FIG. 6. The spectrum confirms that light was emitted from thenanocrystals by electrons applied to the device. In theelectroluminescent spectrum of the device, peak emitting wavelength was520 nm, and the FWHM was approximately 40 nm. In addition, the intensityof the spectrum was 10 Cd/m2 and the efficiency of the device was about0.1%.

Although the preferred embodiments of the present invention have beendisclosed for illustrative purposes, those skilled in the art willappreciate that various modifications, additions and substitutions arepossible, without departing from the scope and spirit of the inventionas disclosed in the accompanying claims.

What is claimed is:
 1. An organic-inorganic hybrid electroluminescentdevice comprising: a semiconductor nanocrystal pattern prepared bycoating a substrate with a dispersion in an organic solvent ofsemiconductor nanocrystals, wherein the semiconductor nanocrystals aresurface-coordinated with a compound containing photosensitive functionalgroups; evaporating the organic solvent to form a film of thesurface-coordinated semiconductor nanocrystals on the substrate;exposing the film to light through a mask; cross-linking thephotosensitive functional groups to form a network structure of thesemiconductor nanocrystals; and developing the exposed film, wherein thecompound containing a photosensitive functional group is represented byFormula 1 below:X-A-B  (1), wherein X is NC—, HOOC—, HRN—, POOOH—, RS— or RSS—, in whichR is a hydrogen atom or a C_(1˜10) saturated or unsaturated aliphatichydrocarbon group; A is a direct bond, a saturated aliphatic hydrocarbongroup, a phenylene group, a biphenylene group, an aliphatic ester group,an aliphatic amide group, an aliphatic oxycarbonyl group or an aliphaticether group; and B is an organic group containing at least onecarbon-carbon double bond, which may be substituted with at least onegroup selected from the group consisting of —CN, —COOH, halogen groups,C_(1˜5) halogenated alkyl groups, amine groups, C_(6˜15) aromatichydrocarbon groups, and C_(6˜12) aromatic hydrocarbon groups substitutedwith F, Cl, Br, a halogenated alkyl group, R′O—, in which R′ is ahydrogen atom or a C_(1˜5) alkyl group, —COOH, an amine group, or —NO₂.2. The organic-inorganic hybrid electroluminescent device according toclaim 1, wherein the moiety B in Formula 1 is an organic grouprepresented by Formula 2 below:—CR₁═CR₂R₃  (2) wherein R₁ is a hydrogen atom, —COOH, a halogen group, aC_(1˜5) alkyl group or a halogenated alkyl group; and R₂ and R₃ are eachindependently a hydrogen atom, a C_(1˜30) alkyl group, —CN, —COOH, ahalogen group, a C_(1˜5) halogenated alkyl group, a C_(2˜30) unsaturatedaliphatic hydrocarbon group containing at least one carbon-carbon doublebond, a C_(6˜12) aromatic hydrocarbon group substituted or unsubstitutedwith F, Cl, Br, hydroxyl, a C_(1˜5) halogenated alkyl group, an aminegroup, R′O—, in which R′ is a C_(1˜5) alkyl group, —COOH, or —NO₂. 3.The organic-inorganic hybrid electroluminescent device according toclaim 1, wherein the compound containing a photosensitive functionalgroup is selected from a group consisting of acrylic acid compounds,unsaturated fatty acid compounds, cinnamic acid compounds, vinylbenzoicacid compounds, acrylonitrile-based compounds, unsaturated nitrile-basedcompounds, unsaturated amine compounds, and unsaturated sulfidecompounds.
 4. The organic-inorganic hybrid electroluminescent deviceaccording to claim 1, wherein the compound containing a photosensitivefunctional group is selected from a group consisting of methacrylicacid, crotonic acid, vinylacetic acid, tiglic acid, 3,3-dimethylacrylicacid, trans-2-pentenoic acid, 4-pentenoic acid,trans-2-methyl-2-pentenoic acid, 2,2-dimethyl-4-pentenoic acid,trans-2-hexenoic acid, trans-3-hexenoic acid, 2-ethyl-2-hexenoic acid,6-heptenoic acid, 2-octenoic acid, citronellic acid, undecylenic acid,myristoleic acid, palmitoleic acid, oleic acid, elaidic acid,cis-11-elcosenoic acid, euric acid, nervonic acid,trans-2,4-pentadienoic acid, 2,4-hexadienoic acid, 2,6-heptadienoicacid, geranic acid, linoleic acid, 11,14-eicosadienoic acid,cis-8,11,14-eicosatrienoic acid, arachidonic acid,cis-5,8,11,14,17-eicosapentaenoic acid,cis-4,7,10,13,16,19-docosahexaenoic acid, fumaric acid, maleic acid,itaconic acid, ciraconic acid, mesaconic acid, trans-glutaconic acid,trans-beta-hydromuconic acid, trans-traumatic acid, trans-muconic acid,cis-aconitic acid, trans-aconitic acid, cis-3-chloroacrylic acid,trans-3-chloroacrylic acid, 2-bromoacrylic acid,2-(trifluoromethyl)acryl-ic acid, trans-styrylacetic acid,trans-cinnamic acid, alpha.-methylcinnamic acid, 2-methylcinnamic acid,2-fluorocinnamic acid, 2-(trifluoromethyl)cinnamic acid,2-chlorocinnamic acid, 2-methoxycinnamic acid, 2-hydroxycinnamic acid,2-nitrocinnamic acid, 2-carboxycinnamic acid, trans-3-fluorocinnamicacid, 3-(trifluoromethyl)cinnamic acid, 3-chlorocinnamic acid,3-bromocinnamic acid, 3-methoxycinnamic acid, 3-hydroxycinnamic acid,3-nitrocinnamic acid, 4-methylcinnamic acid, 4-fluorocinnamic acid,trans-4-(trifluoromethyl)-cinnamic acid, 4-chlorocinnamic acid,4-bromocinnamic acid, 4-methoxycinnamic acid, 4-hydroxycinnamic acid,4-nitrocinnamic acid, 3,3-dimethoxycinnamic acid, 4-vinylbenzoic acid,allyl methyl sulfide, allyl disulfide, diallyl amine, oleylamine,3-amino-1-propanol vinyl ether, 4-chlorocinnamonitrile,4-methoxycinnamonitrile, 3,4-dimethoxycinnamonitrile,4-dimethylaminocinnamonitrile, acrylonitrile, allyl cyanide,crotononitrile, methacrylonitrile, cis-2-pentenenitrile,trans-3-pentenenitrile, 3,7-dimethyl-2,6-octadienenitrile, and1,4-dicyano-2-butene.
 5. The organic-inorganic hybrid electroluminescentdevice according to claim 1, wherein the semiconductor nanocrystalcomprises CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, HgS, HgSe, HgTe, GaN, GaP,GaAs, InP, InAs, or a mixture thereof.
 6. The organic-inorganic hybridelectroluminescent device according to claim 5, wherein thesemiconductor nanocrystal comprises at least two compounds selected fromthe group consisting of CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, HgS, HgSe,HgTe, GaN, GaP, GaAs, InP and InAs, and is a uniformly mixed type,gradiently mixed type, core-shell type, or alloy type.
 7. An article,comprising: a semiconductor nanocrystal pattern prepared by coating asubstrate with a dispersion in an organic solvent of semiconductornanocrystals, wherein the semiconductor nanocrystals aresurface-coordinated with a compound containing photosensitive functionalgroups; evaporating the organic solvent to form a film of thesurface-coordinated semiconductor nanocrystals on the substrate;exposing the film to light through a mask; cross-linking thephotosensitive functional groups to form a network structure of thesemiconductor nanocrystals; and developing the exposed film, wherein thecompound containing a photosensitive functional group is represented byFormula 1 below:X-A-B  (1), wherein X is NC—, HOOC—, HRN—, POOOH—, RS— or RSS—, in whichR is a hydrogen atom or a C_(1˜10) saturated or unsaturated aliphatichydrocarbon group; A is a direct bond, a saturated aliphatic hydrocarbongroup, a phenylene group, a biphenylene group, an aliphatic ester group,an aliphatic amide group, an aliphatic oxycarbonyl group or an aliphaticether group; and B is an organic group containing at least onecarbon-carbon double bond, which may be substituted with at least onegroup selected from the group consisting of —CN, —COOH, halogen groups,C_(1˜5) halogenated alkyl groups, amine groups, C_(6˜15) aromatichydrocarbon groups, and C_(6˜12) aromatic hydrocarbon groups substitutedwith F, Cl, Br, a halogenated alkyl group, R′O—, in which R′ is ahydrogen atom or a C_(1˜5) alkyl group, —COOH, an amine group, or —NO₂.8. The organic-inorganic hybrid electroluminescent device of claim 1,wherein the exposing further comprises exposing the film at an exposuredose of 50 millijoules per square centimeter to 850 millijoules persquare centimeter.
 9. The organic-inorganic hybrid electroluminescentdevice of claim 1, wherein the exposing further comprises exposing thefilm to light having a wavelength of 200 nanometers to 500 nanometersand an energy of 100 watts to 800 watts.